Continuous peroxide bleaching of cross linked cellulose fabrics



Sep'c., 317, 1963 L. v. MGMACKIN 3,104,152

CONTINUOUS PEROXIDE BLEACHING oF CROSS LINKED cELLULosE FABRICS www. da Vf 772i gm Sept. 17, i963 l.. v. MoMAcKlN 3,104,152

CONTINUOUS PEROXIDE BLEACHING OF CROSS LINKED CELLULOSE FABRICS Flled Aug. 50. 1961 3 Sheets-Sheet 2 @LA DRV/N@ 575/2 j Sep-n 17, 1963 L. v. MCMACKIN CONTINUOUS PEROXIDE BLEACHING oF cRoss LINKED CELLULOSE FABRICS 3 Sheets-Sheet 3 Filed Aug. 30. 1961 IN VEN TOR. ffjlfac/fl.;

United States Patent O 3,134,152 CONTINUOUS PERXHDE BLEACHG 0F CRSS LINKED CELLULQSE FABRICS Luther V. McMacltin, Lancaster, S.C., assignor to The Springs Cotton Mills, a corporation of South Carolina Filed Aug. 30, 1961, Ser. No. 134,980 3 Claims. (Cl. 8-111} The present invention relates to wash and wear fabric, and more particularly to a method for obtaining irnproved cellulosic Iwash and wear bleached fabric, in which the cellulose molecules have been cross linked by a che-micall reactant.

There are two general methods for obtaining wash and wear finishes on textile fabrics. The first of these is the application of resins to the surface of a pre-bleached textile fabric, and in which discoloration does not result and subsequent bleaching is not requi-red.

The second method lfor obtaining wash :and wear iinishes lis one in which pre-bleached cellulosic fabric is reacted lwith a chemical that cross links the cellulose molecules. This process presents an important problem in that the cellulosic fabric is discolored Iby the chemical reaction, land thus subsequent bleaching is required.

Several attempts have been `made to 'bleach `fabrics having chemically cross linked cellulose molecules, such yas conventional wet bleaching, boiling in bleach, and padding cold bleach onto the fabric and holding -it in rolled form for a period of time, but all of the -methods have disadvantages, such as being too slow for commercial purposes, damaging, the wash and wear finish, `and providing too low `a degree of whiteness.

We have discovered a very satisfactory procedure for bleaching .cellulosic fabrics to which have been imparted a ,wash `and wear (wrinkle resistant) finish by chemically oross linking the cellulose molecules. We have found that such lfabrics may be bleached with hydrogen peroxide in open width in a continuous process on hot cans, such as are most commonly used for drying fabrics, and that this overcomes the problems of insufficient speed and `damage to the wash and wear finished fabric.

We have `also discovered that the eciency of the peroxide bleaching and the ultimate whiteness of the wash and wear fab-ric are substantially improved by carrying out the treatment of the fabric in two consecutive stages. In the first stage, the fabric is saturated with a bleaching kcomposition containing hydrogen peroxide, and is then heated to substantial dryness, i.e. to a moisture content of :about 2%-3% of the weight of the fabric. The thus treated fabric is then wet with an laqueous solution following which the fabric is heated again to substantial dryness. This procedure markedly improves the efficacy of the hydrogen peroxide and the bleaching of the fabric to desired whiteness, suitable for use in `mens white shirts, etc.

An illustrative but non-limiting embodiment of the process of this invention is shown in the accompanying drawings, in which:

FIG. 1a is la flow chant showing the first stage of the fabric treatment;

FlG. lb is a continuation of the flow chart of FIG. la `showing the second stage of the `fabric treatment; and

FIG. 2 is -a diagrammatic view of a portion of la 4bleaching range illustrating generally the equipment used in the two stage operation of the present invention.

According to the process of the present invention, open width, pre-bleached, woven, white, dry, cotton shirting is passed continuously at a speed of 90 yards per minute through guide rolls and into a pad box containing the following composition lat 100 F., for imparting Wash and SAM-52 Patented Sept. 17, 1963 r'ce wear effects, all parts 'by weight, and which may be compounded by mixing together the following components, in the order listed:

Wetting agent (1,1,3,3 tetr-amethylbutyl phenoxypolyethoxyethanol) The shirting is then passed through squeeze rolls adjusted to allow the fabric to retain about 65 %-70% of its own weight of the sulfcnyldiethanol composition and then passed by :means of a clip tenter `frame for 90 feet through an area of -blown hot air at 225 F. to 265 F., whereby the Ifabric -is dried to about 5% moisture content, and then passed over a three roll calender.

The fabric is then passed through a gas fired curing oven continuously containing 150 yards of fabric and heated to 355 F. The curing temperature is critical in that below 345 F. the sulfonyldieth-anol will not react with the cotton shifting to cross link the cellulose molecules, and lat temperatures of more than 365 F. a cross shading of the fabric occurs that cannot be removed by subsequent bleaching. The `fabric is then passed over three cooling cans, through which are circulated water at tap temperature, and then collected on `a take up roll, at which Itime it may be stored indefinitely or taken immediately to the bleaching operation. It will be noted that the previously white cotton shirting is discolored to ya creamcolor upon emergence from the Icuring oven, and that it is the thus discolored fabric that has proven so dicult to bleach.

All of the above oper-ations have been carried out in a continuous process with the fabric traveling at a rate of yards per minute.

The cotton shirting is next put through a scouring operation prior to the bleaching. We have found that the scouring is import-ant .for satisfactory subsequent bleaching. The scouring is accomplished by passing the fabric in open width continuously `at a speed of yards per minute over `guide means and into a pad box containing, at F., one gallon of concentrated acetic acid (84%), l0 pounds of detergent (33% aqueous dispersion of sodium-N-methyl-N-oleoyl laura-te), and water to bring the final volume to 250 gallons, and then through squeeze rol-ls `and into five successive wash boxes, each equipped with squeeze rolls at its entry and em't and containing 250 gallons of Water at 165 F. The exit squeeze roll of the last box is adjusted to :allow the fabric to retain about 50% yof its weight in water. The fabric passes out `onto a `conventional scray to interrupt the tension.

The fabric 10 is then passed over guide means 11.--13 and, while still retaining about 50% water, into la pad Lbox 14 containing the `aqueous bleaching composition. The bleaching composition is maintained at 100 F. and is continuously fed chemicals so that it has the following constant composition:

Lbs. 50% hydrogen peroxide in water 62 Wett-ing Iagent (1,l,3,3 tetramethylbutyl-phenoxy-polyethoxyethanol) Soda yash (99% NagCOa) 3 Sodium tripolyphosphate 50 Qs. H2O to give 250 gallons nal volume.

The `fabric is passed through squeeze rolls 15 adjusted to allow it to emerge from the aqueous bleaching solution with about 36% of its own weight of water and aqueous bleaching solution. rfhe fabric 10 is next passed over guides 16 and 17 and overa conventional adjustable ten- Sion device 18, and is then serpentined through `a network of twenty three conventional steam heated, cylindrical, rotating drying cans 19-41 in Contact with the sur. faces thereof. Each drying can is 72.3 in circumference and is maintained at 45 pounds per square inch internal steam pressure. The fabric remains on the above drying pans 19-41 for about 15 seconds, where the fabric is partially bleached, but not to the degree of Whiteness desired. The fabric lila emerges from drying can -1 containing about 2%-3% of its weight in residual bleach and water, `about 90%-94% of the moisture content prior to can drying having been duiven olf of the fabric, and at which moisture content rapid bleaching has ceased for Iall practical purposes.

riChe bleaching treatment is then renewed by passing the fabric a into a trough 42 containing water 43 at tap temperature. This rewetting renews the action of the hydrogen peroxide and the wetted fabric then passes through squeeze rolls 44 adjusted to allow about 35% water and residual bleach retention based on the weight of the goods. While some of the bleaching composition may be removed `from the fabric during the rewetting step, enough res-idual bleach remains on the fabric to provide the essential subsequent bleaching. The fabric 10b is passed over a series of expanders 4S, and is then serpentined through la network of twenty one steam heated, cylindrical, rotating `drying cans 4666, in contact with the surfaces thereof. Each drying can is 72.3 in circumference and lis maintained -at 45 pounds per square inch internal steam pressure. The fabric remains on the drying cans 46-66 for about 13-14 seconds Iand emerges from drying can 66 substantially dry and in fully and evenly bleached bright white condition. The fab-ric is passed over three cooling cans 67-69, each of which is 72.3 in circumference and contains therein circulating water at tap temperature. The fabric is collected on a take up roll, 4and may be taken immediately into Ia scouring and top finishing operation or may be stored for a period of time if convenience dictates. In any event it is desirable to wash residual chemicals from the fabric to prevent damage, but we have allowed the rolled fabric with residual chemicals to stand for as long as 36 hours without damage. It will be understood that Vthe `above collection on -a take up `roll may be omitted if the equipment is arranged to allow the fabric to pass directly into a scouring operation, such las follows.

rFhe fabric is next scoured by passing it continuously in open width, :at the rate of 150 yard-syper minute, over guide means 'and into a pad box containing, at 165 F one gallon of concentrated acetic acid (84%), 10 pounds of detergent (33% aqueous dispersion of sodium-N- methyl-N-oleoyl laurate), and water tto bring the final volume -to 250 gallons, and then through squeeze rolls and into five successive wash boxes, each equipped with squeeze rolls at its `entry and exit, and containing water at 165 F.

The fabric is then dried to substantial dryness fby passing it over twenty conventional steam heated, cylindrical, rota-ting, drying cans, in the above described manner, each being 72.3 in circumference and having van internal steam pressure of 4 lbs-10 lbs. per square inch.

The dry fabric Iis passed over guide means and `into a padder containing a top softener and fluorescent brightener composition at 110 F. The composition may be formed by mixing together the following components in the order listed:

Fluorescent brightener (25% aqueous dispersion of bis(2 anilino para sodium sul-phonate 4- monoethanolamino 6 triazinyl) 4,4 diaminostilbene-2,2disodium sulphonate) fl. oz 30 Non-ionic wetting agent (sodium fdcaprylsulfosuccinate) bs-- Q.s. H2O to give nal volume of 250 gallons.

The fabric is passed through squeeze rolls adjusted to allow the fabric to lretain 65 %-70% of its own weight of the top softener rand fluorescent brightener composition. The fabric is next ydried to 5% moisture content by passing it on a clip tenter frame under a zone of hot air at 250 F. to 300 F., and finally thev fabric with 5% moisture content is passed through :a compressive shrinkage machine equipped with a rubber belt.

It will be noted that the fabric, after being collected from the curing oven, has been processed while traveling 'at fa rate of 15 0 yards per minute.

The cotton shirting produced according to the above process has outstanding bright whiteness, `excellent crease resistance in both the wet and dry states, is free from odor, and will shrink less than 0.75%. The Wash vand wear iinish is permanent since the sulfonyldiet-hanol has reacted chemically to cross link the cellulose molecules.

I claim:

1. In the method of obtaining .a white wash :and wear cellulosic fabric wherein the cellulose is cross linked by a chemical reactant and the `fabric is thereafter bleached, the improvement :characterized in that the bleaching is a continuous open width process comprising the steps of impregnating a cross linked and subsequently scoured cellulosic fabric, lcontaining @about 50% of its weight in water, with an alkaline aqueous hydrogen peroxide bleaching composition containing about 3% Iby weight of 50% hydrogen peroxide; squeezing the fabric until it contains about 36% of its weight in water :and bleaching composition; passing the fabric over and in contact with la network of heated cylindrical drying cans for about 15 seconds whereby the fabric is fdried to about 2-3% of its weight in water and residual bleaching composition and partially bleached; impregnating the fabric with water; squeezing the fabric until it contains about 35% of its weight in water and residual bleaching composition; passing the fabric over `and in contact with a network of heated cylindrical drying cans for about 13-14 seconds whereby ythe fabric is bleached to a bright white con-dition and substantially dried; tand thereafter scouring and drying said fabric.

2. The method #according to claim 1 and further characterized in that the cellulose is cross linked with 2,2- sulfonyldiethanol.

3. The method according .to claim 1 and further characterized in that said alkaline iaqueous hydrogen peroxide bleaching composition comprises hydrogen peroxide, wetting agent, soda :as-h, and sodium tripolyphosphate.

References Cited in the file of this patent UNITED STATES PATENTS 2,267,276 Hager Dec. 23, Y1941 2,858,183 Potter Oct. 28, 1958 2,972,611 Zweidler Feb. 21, 1961 12,983,568 Nerney et tal May 9, 1961 3,026,166 Gallagher Mar. 20, 1962 FOREIGN PATENTS v 1,227,817 France June 19, 1959 OTHER REFERENCES v ,'Dorest: The Textile Manu-facturer, May 1954, page 254.

Andrews et al.: Textile Research J., Vol. 32, No. 6, June 1962, pages 489-496. f v

Ward Chemistry and Chemical Technology `of Cotton, pages 507-509, pub. 1955 by Interscience Publishers Inc., New York. (TS-1542W2 C. 2 land Div. 43.) 

1. IN THE METHOD OF OBTAINING A WHITE WASH AND WEAR CELLULOSIC FIBRIC WHEREIN THE CELLULOSE IS CROSS LINKED BY A CHEMICAL REACTANT AND THE FABRIC IS THEREAFTER BLEACHED, THE IMPROVEMENT CHARACTERIZED IN THAT THE BLEACHING IS A CONTINUOUS OPEN WIDTH PROCESS COMPRISING THE STEPS OF IMPREGNATING A CROSS LINKED AND SUBSEQUENTLY SCOURED CELLULOSIC FABRIC, CONTAINING ABOUT 50% OF ITS WEIGHT IN WATER, WITH AN ALKALINE AQUEOUS HYDROGEN PEROXIDE BLEACHING COMPOSITION CONTAINING ABOUT 3% BY WEIGHT OF 50% HYDROGEN PEROXIDE; SQUEEZING THE FABRIC UNTIL IT CONTAINS ABOUT 36% OF ITS WEIGHT IN WATER AND BLEACHING COMPOSITION; PASSING THE FABRIC OVER AND IN CONTACT WITH A NETWORK OF HEATED CYLINERICAL DRYING CANS FOR ABOUT 15 SECONDS WHEREBY THE FABRIC OVER AND IN CONTACT WITH A NETWEIGHT IS WATER AND RESIDUAL BLEACHING COMPOSITION AND PARTIALLY BLEACHED; IMPREGNATING THE FABRIC WITH WATER; SQUEEZING THE FABRIC UNTIL IT CONTAINS ABOUT 35% OF ITS WEIGHT IN WATER AND RESIDUAL BLEACHING COMPOSITION; PASSING THE FABRIC OVER AND IN CONTACT WITH A NETWORK OF HEATED CYLIDNERICAL DRYING CANS FOR ABOUT 13-14 SECONDS WHEREBY THE FABRIC IS BLEACHED TO A BRIGHT WHITE CONDITION AND SUBSTANTIALLY DRIED; AND THEREAFTER SCOURING AND DRYING SAID FABRIC. 